Pylance behaviour on overloads doesn't match pyrights behaviour

[yowoda]

Environment data

• Language Server version: 2024.8.1
• OS and version: win32 x64
• Python version (and distribution if applicable, e.g. Anaconda):
• python.analysis.indexing: true
• python.analysis.typeCheckingMode: off

Code Snippet

import typing as t
from typing_extensions import ParamSpec, Concatenate

_OriginArgsP = ParamSpec("_OriginArgsP")
_OriginSelfT = t.TypeVar("_OriginSelfT")
_OriginReturnT = t.TypeVar("_OriginReturnT")

_TargetSelfT = t.TypeVar("_TargetSelfT")
_TargetArgsP = ParamSpec("_TargetArgsP")
_NewReturnT = t.TypeVar("_NewReturnT")

@t.overload
def copy_method_signature(
    origin: t.Callable[Concatenate[_OriginSelfT, _OriginArgsP], _OriginReturnT], *, return_type: None=..., skip_self: t.Literal[False]=...
) -> t.Callable[[t.Callable[Concatenate[_TargetSelfT, _TargetArgsP], t.Any]], t.Callable[Concatenate[_TargetSelfT, _OriginArgsP], _OriginReturnT]]:
    """A method copies the full signature from another method"""

@t.overload
def copy_method_signature(
    origin: t.Callable[Concatenate[_OriginSelfT, _OriginArgsP], _OriginReturnT], *, return_type: type[_NewReturnT], skip_self: t.Literal[False]=...
) -> t.Callable[[t.Callable[Concatenate[_TargetSelfT, _TargetArgsP], t.Any]], t.Callable[Concatenate[_TargetSelfT, _OriginArgsP], _NewReturnT]]:
    """A method copies the parameter signature from another method but overrides the return type"""

@t.overload
def copy_method_signature(
    origin: t.Callable[Concatenate[_OriginSelfT, _OriginArgsP], _OriginReturnT], *, return_type: None=..., skip_self: t.Literal[True]
) -> t.Callable[[t.Callable[_TargetArgsP, t.Any]], t.Callable[_OriginArgsP, _OriginReturnT]]:
    """A function copies the full signature from another method"""

@t.overload
def copy_method_signature(
    origin: t.Callable[Concatenate[_OriginSelfT, _OriginArgsP], _OriginReturnT], *, return_type: type[_NewReturnT], skip_self: t.Literal[True]
) -> t.Callable[[t.Callable[_TargetArgsP, t.Any]], t.Callable[_OriginArgsP, _NewReturnT]]:
    """A function copies the paramater signature from another method but overrides the return type"""

@t.no_type_check
def copy_method_signature(
    origin, *, return_type=None, skip_self=False
):
    @t.no_type_check
    def inner(target):
        return target
    
    return inner

class A:
    @t.overload
    def method(self, a: int)  -> None:
        ...

    @t.overload
    def method(self, a: str) -> int:
        ...

    def method(self, a: t.Union[int, str]) -> t.Optional[int]:
        ...

@copy_method_signature(A.method, return_type=int, skip_self=True)
@t.no_type_check
def hello(*args, **kwargs):
    ...


reveal_type(hello)

Repro Steps

1. Hover over the copy_method_signature decorator

Expected behavior

No error

Actual behavior

No overloads for "copy_method_signature" match the provided argumentsPylance[reportCallIssue](https://github.com/microsoft/pyright/blob/main/docs/configuration.md#reportCallIssue) method.py(31, 5): Overload 4 is the closest match

2. Hover over the reveal_type call

Expected behaviour

Overload[(a: int) -> int, (a: str) -> int] as pointed out by pyright in the command line:
method.py:64:13 - information: Type of "hello" is "Overload[(a: int) -> int, (a: str) -> int]" 0 errors, 0 warnings, 1 information

Actual behaviour

Type of "hello" is "(...) -> None"

Logs

XXX

[yowoda]

This only seems to happen if you pass in arguments to the copy_method_signature call

@copy_method_signature(A.method)
@t.no_type_check
def hello(*args, **kwargs):
    ...

pylance seems to have no problem with this

[bschnurr]

thanks for the report. pylance didn't get update last week and I think pyright recently updated its overload logic, so I'm guessing that is the reason for the disagreement. In the mean time you can check which version of pyright pylance is using in the python language server output window.

[yowoda]

Yup, pylance is using version 1.1.373, seems like this bug was fixed in pyright version 1.1.374

[debonte]

Yup, pylance is using version 1.1.373, seems like this bug was fixed in pyright version 1.1.374

Pylance's latest prerelease build (2024.8.101) is using Pyright 1.1.375.

[yowoda]

Ah yep, can confirm it's working on the prerelease build, thanks a lot!